Means for obtaining smooth wood flakes while producing a flat surface wood



July 26, 1966 JQHNSQ 3,262,476 MEANS FOR OBTAININ MOOTH D AKES WHILE PRODUCING A FLAT FACE WOOD Filed Dec. 11, 1965 5 Sheets-Sheet l "llllIli,

INVENTOR. DONALD L. JOHNSON ATTORNEY July 26, 1966 D. JOHNSON 3,262,476

NG SMOOTH FL MEANS FOR OBTA WOOD AKES WHILE PROD NG A FLAT SURFACE WOOD Filed Dec. 11, 1963 5 Sheets-Sheet 2 ATTORNEY L. JOHNSON 5 Sheets-Sheet 5 D MEANS FOR OBTAINING SMOOTH WOOD FLAKES WHILE PRODUCING A FLAT SURFACE WOOD July 26, 1966 Filed D60. ll, 1965 INVEN TOR. DONALD l... JOHNSON ATTORNEY United States Patent 3,262,475 MEANS FOR OBTAINING SMOOTH WOOD FLAKES WHILE PRODUOING A FLAT SURFACE WOOD Donald L. Johnson, 1340 Heatherwood W Tacoma, Wash. Filed Dec. 11, 1963, Ser. No. 329,665 8 Claims. (Cl. 144-176) This invention relates to the producing of wood flakes and the cutting of a flat surface on wood with the employment of a rotary cutter having slicing knives with substantially radially-extending cutting edges with the cutting edges arranged in a helical-spiral, radially-retreating, axially advancing knife line, and with the wood, from which the flakes are cut and on which the flat surface is produced by the cutter, being moved relatively with respect to the cutter head in a direction perpendicular to the axis of rotation of the cutter head and at a speed synchronized with the rotary speed of the cutter head.

The present invention accordingly is related to the inventions described in my U.S. Letters Patent Nos. 2,889,859, issued June 9, 1959, No. 2,949,946, issued August 23, 1960, No. 2,964,079, issued December 13, 1960, and also to my pending application for patent, Serial No. 279,411, filed May 10, 1963, entitled, Apparatus for Flaking and Surfacing Wood. These prior patents and pending application describe the cutting of wood flakes and the producing of a flat surface on wood by similar rotary cutters operating in a similar manner. While the devices and the general method described in these prior patents and application are capable of producing wood flakes while cutting a flat surface on wood and the resulting flakes have been entirely satisfactory as long as the cutter head knives are so set as to cutthin flakes, it has nevertheless been found that when attempts are made to cut thicker flakes, for example flakes above .05 of an inch in thickness, for many species of wood, a somewhat rough surface is produced on the wood and flakes, and furthermore some slivers or fines are produced with the cutting of the thicker flakes. Consequently, although thicker wood flakes have been desired in some cases, the fact that their surfaces have been less smooth than the thinner flakes and thefact that undesirable fines and slivers have resulted from the cutting of the thicker flakes, have resulted heretofore in the production of the thicker flakes being less satisfactory than in the case of the thin flakes for which the earlier cutters were designed.

The general object of the present invention accordingly is to provide an improvement in the method and means for cutting desired wood flakes while producing a flat surface on wood which will enable thicker wood flakes to be produced as satisfactorily as the thinner flakes.

When thicker wood flakes are cut with the flaker-surfacer or rotary cutter described .in my above mentioned pending application Serial No. 279,411, or with the flakersurfacers described in my previous patents above mentioned, the thicker wood flakes, having greater stiffness and resistance to flexure than the thin flakes, have a tendency to split off ahead of the cutting edge of the knife and in so doing will sometimes tear out a little wood below the plane of the cutting edge. This results in depressions or hollows on the surface 'of the wood and corresponding projections on the flakes in the immediate path of the cutting edges of the knives as the flakes are sliced off by the knives and produces undesired slivers and fines mixed with the flakes. I had observed that in the slicing of veneer sheets from logs the wood surface should be compressed in the area where the slicing is taking place, and it occurred to me therefore that this same general principle might be followed in the cutting of wood flakes so as to prevent the undesirable splitting of the flakes from the wood immediately ahead of the cutting knife. Experiments and tests proved my theory to be correct.

A more specific object of this invention consequently is to provide an improved flatter-surface capable of more satisfactorily producing thicker wood flakes by compressing and confining the wood where the slicing of each flake occurs.

Another problem which presented itself when attempts were made to produce thicker flakes with my previous flaker-surfacers was caused by the fact that the relatively thick flakes were found to expand slightly in thickness, were generally wet and compressible, and sometimes pitchy, all of which contributed in causing the thicker flakes to have a tendency to adhere to the sides of the discharge passages in the cutter head and to clog the slot opening at each knife blade.

A further object of the present invention is to provide an imporved flaker-surf'acer or cutter head in which any clogging of the discharge passages or slots will be prevented by having the same increase in size towards their discharge ends.

In the cutting of uniform flakes with a cutter head having an axially-advancing, radially-retreating knife line, such as described in 'my above mentioned prior patents and pending application, it is important to have the knives very accurately set along the desired axiallyadvancing cutting path, otherwise non-uniform flakes and rough surfaces will be cut. However, in my previous fiaker-surfacers this accurate setting of the knife bars has required special care and considerable time. Therefore an additional object of the present invention is to provide improved method and means for facilitating the accurate setting of the knives in place.

These objects and incidental advantages are attained through the method and means herein briefly described with reference to the accompanying drawings, wherein:

FIG. 1 is a diagrammatic view illustrating in general the operation a flaker-surfacer or a cutter head of this type for producing wood flakes while also cutting a flat surface on a log of wood;

FIG. 2 is a fragmentary elevational view of the working face of the improved cutter head or flaker-surfacer of the present invention;

FIG. 3 is' a developed fragmentary side view of the cutterv head, drawn to a larger scale, showing that portion of the cutter head assembly indicated by the line 3-3 in FIG. 2;

FIG. 4 is a fragmentary section taken along one of the knife-receiving slots in the cutter head, taken on the line indicated at 44 in FIG. 3, looking in the direction indicated by the arrows, drawn to a larger scale, and showing a knife barand associated pressure bar in place in their slots in the cutter head;

FIG. 5 is a fragmentary section taken on the line indicated at 55 in FIG. 3, drawn to the same scale as FIG. 4, and showing a cross section of the same knife bar and pressure bar;

FIG. 6 is an elevation of the lower side of one of the knife bars drawn to the same scale as FIG. 4;

FIG. 7 is an elevation of the opposite side of the knife bar;

FIG. 8 is an elevation of a lower side of a pressure bar;

FIG. 9 is an elevation of the opposite side of the pressure bar;

FIG. 10 is a fragmentary transverse section on the line indicated at 1010 in FIG. 3;

FIG. 11 is a staggered fragmentary section on the line indicated at 1111 in FIG. 2;

FIG. 12 is a fragmentary section on line 1212 of FIG. 2 drawn to a considerably enlarged scale illustrating the cutting of wood flakes with the cutter head of the present invention with the employment of cooperating pressure bars; and

FIG. 13 is a comparative corresponding fragmentary sectional view drawn to the same scale illustrating the cutting of wood flakes by the prior rotary cutters without the special pressure bars.

The cutter head body 25, illustrated diagrammatically in FIG. 1 and shown in part in more detail in FIG. 2, is similar to the cutter heads described in the patents and pending application previously mentioned in that it is formed with a plurality of identical volute portions on the periphery of the cutter head, with the radius in each volute portion decreasing in the direction opposite the direction of rotation of the cutter head. In the particular cutter head illustrated by way of example there are two such volute portions, each extending for 180 on the periphery of the cutter head. One of these is shown entirely in FIG. 2 and is indicated by the reference character 26.

In the example illustrated in the drawings, each of the two volute peripheral portions 26 of the cutter head is provided with twelve equally spaced knife bars 27 (indicated at 1 to 12 inclusive in FIG. 2), and twelve pressure bars 28, later described (indicated at 13 to 24 inclusive in FIG. 2), which pressure bars immediately precede the knife bars respectively in the direction of rotation of the cutter head, the direction of rotation being indicated by the arrows in the figures.

A series of equally-spaced knife slots 29 (FIGS. 2, 3, 4, 5 and 11) and continuing inner slits 30 are cut in each volute peripheral portion and extend in oblique planes arranged all at the same angularity with the axis of rotation of the cutter head. These slots 29 and inwardly continuing slits 30 extend from one face of the volute peripheral portion to the other.

A similar series of equally spaced pressure bar slots 31 and continuing inner slits 32 are also cut in each volute peripheral portion and extend in oblique planes with respect to the axis of rotation of the cutter head body, but (as shown in FIGS. 3 and 11) the slots 31 and slits 32 are arranged at less angularity with respect to the axis of rotation of the cutter head than the slots 29 and inwardly continuing slits 30 for the knives. These slots 31 and slits 32 also extend from one face of the volute peripheral portion to the other. The pair of slots 29 and 31 for each knife and its adjacent, immediately preceding pressure bar, instead of extending to the outer periphery of the volute portion, terminate in a recess 33 (FIGS. 3, 5 and 11), cut in the periphery of the volute portion and extending from one face of the volute portion to the other. The side walls of each recess 33 are parallel to the opposite side walls of the knife slot 29 and pressure bar slot 31 respectively. Consequently the width of each recess 33 increases from the working face of the volute portion to the opposite face of the volute portion. The knife slots 29 and pressure bar slots 31, and their inwardly continuing slits 30 and 32 respectively, are curved in their respective planes to correspond to the curvature of the side edges of the knives and pressure bars. As shown in FIGS. 6 and 7 the edges of each knife bar 27 are curved in the plane of the knife bar, the knife bars in this respect being similar to those described in the previously mentioned pending application Serial No. 279,411, and the edges of the pressure bars 28 are similarly curved, as shown in FIGS. 8 and 9.

FIGS. 6 and 7 show the lower and upper sides of one of the knife bars 27, FIG. 6 showing the cutting knife blade 34 of the knife bar, the cutting blade preferably having a peripheral cutting spur 35 similar to one of the blade spurs described in pending application Serial No. 379,411. Serrations 36 extend along the inner edge or root portion of the upper side of the knife bar, as shown in FIG. 7, to mate with corresponding serrations along the upper wall of the knife bar slot 29.

FIGS. 8 and 9 show upper and lower sides of one of the cooperating pressure bars 28, the lower side of each pressure bar having a pressure face 37, the function of which will presently be explained. Serrations 38 similarly extend along the inner edge or root portion of the lower side of the knife bar as shown in FIG. 8 to mate with corresponding serrations along the lower wall of the pressure bar slot 31.

As shown best in FIGS. 3 and 11 (and also in FIG. 12), the slots for each knife 27 and its associated pressure bar 28 are so arranged that the cutting edge of the knife blade 34 and the adjacent edge of the pressure face 37 of the pressure bar will be spaced apart a distance slightly greater than the thickness of the flakes being cut by the knife blade, the thickness of the flakes being determined by the extent to which each knife blade is extended towards the work or wood in the axial direction with respect to the rotating cutter head. This spacing between the knife bar and its associated pressure bar, due to the fact that the slots for the knife bar and pressure bar diverge in the recess 33, increases from the working face of the volute portion of the cutter head to the opposite face and is an important feature'since this prevents any possible clogging in the spacing between the knife bar and pressure bar along which the flakes travel and from which they are discharged.

The function of the pressure bars will now be explained more fully with reference to FIGS. 12 and 13. FIG. 13 illustrates how the cutting of thick flakes 39, instead of thin flakes, from the wood W, by adjusting the knife bars 40 of a prior cutter head of this general type for producing thicker flakes resulted in rough surfaced flakes and, as mentioned earlier, also resulted in undesired slivers and fines with the slicing of the thick flakes from the wood. FIG. 12 illustrates the method of the present invention with the knife bar 27 and pressure bar 28 set for cutting flakes 39 of the same desired thickness. Here the heel or rear edge 37' of the pressure face 37 of the pressure bar 28 presses down and compresses the flake as it is cut by the knife blade, with the result that a relatively smooth surfaced thick flake is produced without being accompanied by any appreciable amount of wood slivers or fines. Immediately following the combined compressing and slicing of the wood flakes the decompression of the cut flakes occurs as the flakes are thrust along the widening passageway between the pressure bar and the knife bar.

It will be noted in FIG. 12 that the pressure face 37 of the pressure bar 28 has a slight angularity (for example 2) with the plane of rotation, and thus with the surface of the wood which it engages, so that the actual compressing engagement is performed by the end or heel portion of the pressure bar face. This not only reduces the amount of friction but, as will be apparent, also facilitates the desired confining and compressing operation and imposes the compression at the exact spot where it is most effective.

Due to the fact that the volute peripheral portions 26 of the cutter head are provided with the special recesses 33 in which the slots for each knife bar and cooperating pressure bar terminate, the knives in this improved cutter head, unlike those in the cutter heads of the previously mentioned patents and pending application, extend only slightly beyond the cutter head periphery. One advantage of this improved arrangement is that the rapid and accurate setting of the knife bars (and also of the cooperating pressure bars) is facilitated, as presently explained.

In this improved cutter head each of the volute peripheral portions 26 is of less thickness than the inner portion of the cutter head body (see FIGS. 3, l0 and 11). Furthermore the working face of each volute portion is formed with a series of cutbacks 41 (FIG. 3) corresponding to the number of knives, each cutback retreating from the preceding cutback a'distance equal exactly to the desired flake thickness for the cutting of which the particular cutter head is designed. Looking at this in another way, the cutbacks constitute steps in the Working face of each volute portion, advancing in an axial direction with respect to the axis of rotation of the cutter head in the same way as the cutting edges of the successive knives advance to produce the axially-advancing, as well as radially-retreating, knife line which is essential in the flaking and surfacing of wood with devices of this type.

This unique arrangement of the working face of each volute portion with respect to the cutting knives considerably facilitates the accurate setting of the knives (and similarly of the pressure bars) in proper position in their slots. It has been found that a skilled mechanic can feel a very small difference in elevation between two surfaces, especially if the surfaces are smooth and flat. Consequently if the cutter head with such volute portions is accurately machined and revolves truely, the cutbacks or steps in the working face of each volute portion serve as means for the accurate and easy setting of the knife bars and pressure bars in proper position.

The opposite or back face of each volute portion 26, as shown in FIG 3, is also formed with corresponding cutbacks or steps 42. This not only removes excess material from the volute portions but also reduces the lineal length of the slot for the knife bars and pressure bars, and these shorter slots mean a saving in time on the part of a Serviceman when knife bars and pressure bars are required to be removed and installed.

The securing of the knife bars and pressure bars in place in the cutter head is obtained by means of clamping bolts 43, similar to the clamping bolts in the cutter head described in pending application Serial No. 279,411, the clamping bolts extending parallel to the axis of rotation of the cutter head and traversing the slits which extend inwardly from the inner ends of the slots for the knife bars and pressure bars.

As previously mentioned, the number of volute peripheral portions with which the cutter head is provided may be varied, and also some minor modifications would be possible in the improved cutter head herein described withoutdeparting from the method and means constituting the present invention.

I claim:

1. In a wood flaking and surfacing device of the character described having a rotating cutter head, a plurality of identical volute portions on the periphery of the cutter head each having a radius decreasing constantly in the direction opposite from the direction of rotation, said volute portions having identical equally-spaced knife slots extending from the working face, said knife slots inclined forwardly in the direction of rotation of said cutter head and extending in planes having the same angularity with the cutter head axis, said volute portions having identical equally-spaced pressure bar slots extending from the working face, each of said pressure bar slots located in advance of a knife bar slot in the direction of rotation of said cutter head, said pressure bar slots inclined forwardly in the direction of rotation of said cutter head and extending in planes having the same angularity with said cutter head axis, and pressure bars and knife bars secured in said pressure bar slots and said knife bar slots respec- 2. In a wood flaking and surfacing device of the character described having a rotating cutter head, a plurality of identical volute portions on the periphery of the cutter head each having a radius decreasing constantly in the direction opposite from the direction of rotation, said volute portions having identical equally-spaced knife slots extending from the working face to the back face of said volute portions, said knife slots inclined forwardly in the direction of rotation of said cutter head and extending in planes having the same angularity with the cutter head axis, said volute portions having identical equallyspaced pressure bar slots extending from the working face to the back face of said volute portions, each of said pressure bar slots located in advance of the knife bar slots in the direction of rotation of said cutter head, said pressure bar slots inclined forwardly in the direction of rotation of said cutter head and extending in planes having the same angularity with said cutter head axis but hav ing slightly less angularity with said axis than said knife bar slots, and pressure bars and knife bars secured in said pressure bar slots and said knife bar slots respectively, each pressure bar having a pressure face and each knife bar having a slicing blade on the working face of a volute portion, said pressure bar slots, knife bar slots, pressure bars and knife bars so arranged that the spacing between the edge of each knife blade and the heel of the associated pressure bar face will be approximately equal to the thickness of the wood flakes sliced by the knife blades, whereby said pressure faces of said pressure bars will exert a slight compressing force on the areas where the slicing takes place, the spacing between each knife bar and the associated pressure bar increasing from the knife blade edge and the pressure'face of the pressure bar to the rear ends of said kriife bar and pressure bar.

3. In a wood flaking and surfacing device of the character described having a rotating cutter head, a plurality of identical volute portions on the periphery of the cutter head each having a radius decreasing constantly in the direction opposite from the direction of rotation, said -volute portions having identical equally-spaced recesses on their peripheries extending from the working face to the back face of said volute portions, the inside wall of each recess having a knife slot extending from the working face of the volute portions, said knife slots inclined forwardly in the direction of rotation of said cutter head and extending in planes having the same angularity with the cutter head axis, said inside wall of each recess having a pressure bar slot, each said pressure bar slots located in advance of the knife bar slot in the direction of rotation of said cutter head, said pressure bar slots inclined forwardly in the direction of rotation of said cutter head and extending in planes having the same angularity with said cutter head but slightly less angularity with said axis than said knife bar slots, and pressure bars and knife bars secured in said pressure bar slots and said knife bar slots respectively, each pressure bar having a pressure face and each knife bar having a slicing blade on the working face of a volute portion, said pressure bar slots, knife bar slots, pressure bars and knife bars so arranged that the spacing between the edge of each knife blade and the heel of the associated pressure bar face will be approximately equal to the thickness of the wood flakes sliced by the knife blades and said pressure faces of said pressure bars will exert a slight compressing force at the areas where the slicing takes place, the spacing between each knife bar and the associated pressure bar within the recess in which they are contained increasing from the knife bar edge and the pressure face of the pressure bar to the rear ends of said pressure bar and knife bar.

4. In a wood flaking and surfacing device of the character described having a rotating cutter head, a plurality of identical volute portions on the periphery of the cutter head each having a radius decreasing constantly in the direction opposite from the direction of rotation, said volute portions having identical equally-spaced recesses on their peripheries extending from the working face to the back face of said volute portions, the width of said recesses increasing from said work face to said back face, the inside wall of each recess having a knife slot extending the full length of the recess, said knife s-lots inclined forwardly in the direction of rotation of said cutter head and extending in planes having the same angularity with the cutter head axis, said inside wall of each recess having a pressure bar slot extending the full length of the recess, each of said pressure bar slots located in advance of a knife bar slot in the direction of rotation of said cutter head, said pressure bar slots inclined forwardly in the direction of rotation of said cutter head and extending in planes having the same angularity with said cutter head axis, the pressure bar slot and the knife bar slot being positioned adjacent the opposite side walls of each recess respectively, and pressure bars and knife bars secured in said pressure bar slots and said knife bar slots respectively and in contact with the side walls respectively of said recesses each pressure bar having a pressure face and each knife bar having a slicing blade on the working face of a volute portion, said pressure bar slots, knife bar slots, pressure bars and knife bars so arranged that the spacing between the edge of each knife blade and the heel of the associated pressure bar face will be approximately equal to the thickness of the wood flakes sliced by the knife blades and said pressure faces of said pressure bars will exert a slight compressing force at the areas where the slicing takes place, the spacing between each knife bar and the associated pressure bar within the recess in which they are contained increasing from the knife bar edge and the pressure face of the pressure bar to the rear ends of said knife bar and pressure bar.

5. The combination set forth in claim 4 with said pressure faces of said pressure bars being inclined slightly to the plane of rotation and thereby causing the compressing pressure on the wood to be exerted mainly by the heel portion of each pressure face of the pressure bar.

6. The combination set forth in claim 1 with the working face of each of said volute peripheral portions having a series of equal setbacks in the direction of rotation of the cutter head, said set backs extending in parallel planes, and with the blade of each knife bar extending in the plane of the setback following the knife bar blade in the direction of rotation, but with the pressure face of the associated pressure bar terminating in the preceding further setback.

7. The combination set forth in claim 2 with the working face of said volute peripheral portions having a series of equal setbacks in the direction of rotation of the cutter head, said setbacks extending in parallel planes, with the blade of each knife bar extending in the plane of the setback following the knife bar blade in the direction of rotation, but with the pressure face of the associated pressure bar terminating in the preceding further setback, and with the back face of each of said peripheral portions similarly having a series of equal setbacks corresponding respectively to the setbacks in said working face of the volute peripheral portions.

8. In a wood flaking and surfacing device of the character described having a rotating cutter head, a plurality of identical volute portions on the periphery of the cutter head each having a radius decreasing constantly in the direction opposite from the direction of rotation, said volute portions having identical equally-spaced recesses on the peripheries extending from the working face to the back face of said volute portions, the width of said recesses increasing from said working face to said back face, the inside wall of each recess having a knife slot extending the full length of the recess, said knife slots inclined forwardly in the direction of rotation of said cutter head and extending in planes having the same angularity with the cutter head axis, said inside wall of each recess having a pressure bar slot extending the full length of the recess, each of said pressure bar slots located in advance of a knife bar slot in the direction of rotation of said cutter head, said pressure bar slots inclined forwardly in the direction of rotation of said cutter head and extending in planes having the same angularity with said cutter head axis but slightly less angularity with said axis than said cutter knife bar slots, the pressure bar slot and the knife bar slot in each of said recesses positioned adjacent the opposite side walls of the recess respectively, pressure bars and knife bars secured in said pressure bar slots and said knife bar slots respectively, each pressure bar having a pressure face and each knife bar having a slicing blade on a working face of a volute portion, said pressure bar slots, knife bar slots, pressure bars and knife bars so arranged that the spacing between the edge of each knife blade and the heel of the associated pressure bar face will be approximately equal to the thickness of the wood flakes sliced by the knife blades and said pressure face will exert a slight compressing force at the area where said slicing takes place, said pressure faces of said pressure bars being inclined slightly to the plane of rotation causing the pressure on the wood to be exerted mainly by the heel portion of each pressure bar, the spacing between each knife bar and its associated pressure bar within the recess in which they are contained increasing from the knife blade edge and the heel of the pressure face of the pressure bar to the rear ends of said knife bar and pressure bar, the working face of each of said volute peripheral portions having a series of equal setbacks extending in parallel planes, the blade of each knife bai' extending in the plane of the setback following the knife bar blade in the direction of rotation, the pressure face of the associated pressure bar terminating in the preceding further setback, and the back face of each of said volute peripheral portions similarly having a series of equal setbacks corresponding respectively to the setbacks in said working face of the volute peripheral portion.

References Cited by the Examiner UNITED STATES PATENTS 2,751,947 6/1956 Wyss 144326 2,889,859 6/1959 Johnson 144l76 2,964,079 12/1960 Johnson 144-176 3,155,130 11/1964 Logan 144326 WILLIAM W. DYER, JR., Primary Examiner.

R. J. ZLOTNIK, Assistant Examiner. 

1. IN A WOOD FLAKING AND SURFACING DEVICE OF THE CHARACTER DESCRIBED HAVING A ROTATING CUTTER HEAD, A PLURALITY OF IDENTICAL VOLUTE PORTIONS ON THE PERIPHERY OF THE CUTTER HEAD EACH HAVING A RADIUS DECREASING CONSTANTLY IN THE DIRECTION OPPOSITE FROM THE DIRECTION OF ROTATION, SAID VOLUTE PORTIONS HAVING IDENTICAL EQUALLY-SPACED KNIFE SLOTS EXTENDING FROM THE WORKING FACE, SAID KNIFE SLOTS INCLINED FORWARDLY IN THE DIRECTION OF ROTATION OF SAID CUTTER HEAD AND EXTENDING IN PLANES HAVING THE SAME ANGULARITY WITH THE CUTTER HEAD AXIS, SAID VOLUTE PORTIONS HAVING IDENTICAL EQUALLY-SPACED PRESSURE BAR SLOTS EXTENDING FROM THE WORKING FACE, EACH OF SAID PRESSURE BAR SLOTS LOCATED IN ADVANCE OF A KNIFE BAR SLOT IN THE DIRECTION OF ROTATION OF SAID CUTTER HEAD, SAID PRESSURE BAR SLOTS INCLINED FORWARDLY IN THE DIRECTION OF ROTATION OF SAID CUTTER HEAD AND EXTENDING IN PLANES HAVING THE SAME ANGULARILTY WITH SAID CUTTER HEAD AXIS, AND PRESSURE BARS AND KNIFE BARS SECURED IN SAID PRESSURE BAR SLOTS AND SAID KNIFE BAR SLOTS RESPECTIVELY, EACH PRESSURE BAR HAVING A PRESSURE FACE AND EACH KNIFE BAR HAVING A SLICING BLADE ON THE WORKING FACE OF A VOLUTE PORTION, SAID PRESSURE BAR SLOTS, KNIFE BAR SLOTS, PRESSURE BARS AND KNIFE BARS SO ARRANGED THAT THE SPACING BETWEEN THE EDGE OF EACH KNIFE BLADE AND THE HEEL OF THE ASSOCIATED PRESSURE BAR FACE WILL BE APPROXIMATELY EQUAL TO THE THICKNESS OF THE WOOD FLAKES SLICED BY THE KNIFE BLADES, WHEREBY SAID PRESSURE FACES OF SAID PRESSURE BARS WILL EXERT A SLIGHT COMPRESSING FORCE ON THE AREAS WHERE THE SLICING TAKES PLACE. 